Abstract 106: Differential Effects of Mild Therapeutic Hypothermia Against Normothermia for Post-Cardiac Arrest Syndrome According to the Severity Scale

Abstract

Introduction: There are few studies on the differential effects of mild therapeutic hypothermia (MTH) according to the risk class in post-cardiac arrest syndrome (PCAS) patients. Objective: The aim of this study was to evaluate the differential effects of MTH against therapeutic normothermia (TN) for PCAS patients according to our risk classification tool (rCAST). Methods: We used data from the out-of-hospital cardiac arrest (OHCA) registry of the Japanese Association for Acute Medicine (JAAM), which is a multi-center, prospective registry of OHCA patients who were transported to critical care medical centers or hospitals with an emergency care department across Japan. We classified eligible PCAS patients treated with MTH or TN on the basis of our rCAST score which was previously developed by us: low severity group (≤5.5), moderate severity group (6-14), and high severity group (≥14.5). The differential effects of MTH vs. TN for their neurological outcome in the 3 severity categories were evaluated by interaction analysis, and the effect of MTH vs. TN in each group was assessed by multivariate logistic regression analysis and propensity score analysis. The good neurological outcome was defined as a Cerebral Performance Categories score ≤2 at 30 days. Results: Among 12,024 OHCA patients in the registry, data of 460 PCAS patients treated by MTH or TN were analyzed (96 patients; the low score, 192; the moderate score, and 172; the high score group). There was a statistically significant interaction effect between MTH/TN and their neurological outcome at 30 days in the 3 categories (p = 0.022). MTH was significantly associated with good neurological outcome at 30 days in PCAS patients of moderate severity group both in the multivariate logistic regression analysis (adjusted odds ratio, 3.09; 95% confidence interval, 1.13-8.49; p = 0.029) and the propensity score analysis (p = 0.030), while it was not in low and high severity group. Conclusions: The effect of MTH in PCAS patients differed according to the severity of PCAS, and MTH was significantly associated with a good neurological outcome as compared to TN in the moderate severity group.